Scaffold locking mechanism with tension indicator

ABSTRACT

A wheeled scaffold assembly includes a locking mechanism to immobilize a scaffold after the scaffold has been positioned to be used as a work platform. The scaffold assembly may include multiple locking mechanisms. Further, the locking mechanism may include an indication to provide visual confirmation that the locking mechanism is appropriately engaged.

This application claims the benefit, under 35 U.S.C. §119(e), of U.S. Provisional Patent Application Nos. 60/673,860 filed Apr. 22, 2005 and 60/720,315 filed Sep. 23, 2005, the disclosures of each of which are hereby expressly incorporated by reference herein.

FIELD OF THE DISCLOSURE

The present disclosure relates to a locking mechanism for wheeled scaffolding. More specifically, the disclosure relates to a locking mechanism which is engaged from the scaffold work platform to actuate a locking foot to engage the floor under the scaffolding to immobilize the scaffold.

BACKGROUND

Scaffolding is known to be used as a support platform for workers performing work on elevated work surfaces such as high walls and ceilings. A scaffold structure may include casters to provide for mobility of the scaffold from one location to another location. This is especially useful in situations where workers move regularly in performing their work. For example, when plastering a ceiling, workers cover the area accessible from the scaffold. When it is necessary to move to a new location, the workers utilize the wheels of the scaffold to adjust the position of the scaffold while still occupying the support platform by pulling on the ceiling or wall to move the scaffold to a new location.

Occupational safety regulations have been implemented to address the use of wheeled scaffolds by requiring that the scaffold be locked in place at any time that work is being performed from the support platform. This requirement has driven the use of locking wheels on the scaffold so that when the scaffold has been moved to a new work location, the wheels can be locked to prevent unexpected movement of the scaffold while the work is being completed. The result of these regulations is that workers must now dismount the scaffold to unlock the wheels and reposition a scaffold in a new location. This, in turn, reduces the efficiency of the worker, due to the time required for the worker to dismount the scaffold, unlock the wheels, reposition the scaffold, and remount the scaffold to perform work in the new location.

SUMMARY

The present disclosure comprises one or more of the features recited in the appended claims and/or the following features which, alone or in any combination, may comprise patentable subject matter:

According to one aspect of the present disclosure, a scaffold comprises a frame, a platform supported by the frame, a plurality of wheels coupled to the frame, and a locking mechanism coupled to the frame. The locking mechanism may be moveable between a first position wherein the locking mechanism is configured to engage a floor supporting the scaffold and a second position wherein the locking mechanism is configured to be spaced-apart from the floor. The locking mechanism may spring-loaded.

The locking mechanism may further comprise an actuator moveable between a locked position and an unlocked position, a first plunger coupled to the locking handle, the first plunger including a guide portion engaging a second plunger, an extension spring engaging a portion of the first plunger and a portion of the second plunger, the extension spring urging the first plunger and second plunger apart, wherein the second plunger is configured to engage the floor in the locked position and be spaced-apart from the floor in the unlocked position.

In some embodiments, the first plunger may further comprise a first indicator and the second plunger may further comprise a second indicator, the spacing between the first indicator and second indicator indicative of the relative position of the first plunger to the second plunger. In some embodiments, the first indicator may be spaced-apart from the second indicator when the second plunger is in the unlocked position and the first indicator may be aligned with the second indicator when the second plunger is in the locked position. In some embodiments, the distance between the first plunger and second plunger when the locking mechanism is in the unlocked position may be adjustable.

According to another aspect of the present disclosure, a locking mechanism for a scaffold may comprise a mounting bracket configured to be mounted to a scaffold, a first plunger coupled to the mounting bracket, and a second plunger coupled to the first plunger. The first plunger may be moveable relative to the second plunger between an unlocked position wherein a first end of the second plunger is engaged with a second end of the first plunger and a locked position wherein the first end of the second plunger is spaced-apart from the second end of the first plunger. The locking mechanism may further comprise a bias member interposed between a portion of the first plunger and a portion of the second plunger to urge the first and second plungers apart. The floor-engaging member may be spaced-apart from the floor in the unlocked position and is engaged with the floor in the locked position.

In some embodiments, the locking mechanism may further comprise a bias member interposed between a portion of the first plunger and a portion of the second plunger to urge the first and second plungers apart. In some embodiments, the locking mechanism may further comprise an actuator coupled to the first plunger, the actuator configured to move the first plunger between the locked and unlocked positions. The actuator may comprise a toggle lock handle.

In some embodiments, the first plunger may further comprise a first indicator and the second plunger may comprise a second indicator and the spacing between the first indicator and second indicator indicative of the relative position of the first plunger to the second plunger. The first indicator may comprise a tube and the second indicator may comprise a line. In some embodiments, the first indicator may be spaced-apart from the second indicator when the second plunger is in the unlocked position and the first indicator may be aligned with the second indicator when the second plunger is in the locked position.

According to still another aspect of the disclosure, a locking mechanism for a scaffold may comprise a mounting bracket configured to be mounted to a scaffold, a first plunger coupled to the mounting bracket, a second plunger coupled to the first plunger and moveable relative to the plunger, a spring coupled to and positioned between a drive end of the first plunger and a first end of the second plunger. The locking mechanism may be moveable between an unlocked position where the first end of the second plunger is spaced-apart a first distance from the drive end of the first plunger and a locked position where the first end of the second plunger is spaced-apart a second distance less than the first distance from the drive end of the second plunger.

In some embodiments, the first plunger may further comprise a first indicator and the second plunger may further comprise a second indicator. The spacing between the first indicator and second indicator may be indicative of the relative position of the first plunger to the second plunger. In some embodiments, the first indicator may be spaced-apart from the second indicator when the second plunger is in the unlocked position and the first indicator may be aligned with the second indicator when the second plunger is in the locked position. The distance between the first plunger and second plunger when the locking mechanism is in the unlocked position may be adjustable.

According to still another aspect of the disclosure, a method of operating a locking mechanism coupled to a scaffold having a plurality of wheels and moveable relative to a floor supporting the scaffold includes adjusting the locking mechanism to align a first indicator on a first portion of the locking mechanism with a second indicator on a second portion of the locking mechanism when the locking mechanism is in a locked position, positioning the scaffold in a work position, and actuating the locking mechanism to urge a portion of the locking mechanism into engagement with a floor supporting the scaffold to prevent the scaffold from rolling with respect to the floor.

Additional features, which alone or in combination with any other feature(s), including those listed above and those listed in the claims, may comprise patentable subject matter and will become apparent to those skilled in the art upon consideration of the following detailed description of illustrative embodiments exemplifying the best mode of carrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figures in which:

FIG. 1 is a perspective view of a scaffold assembly including a scaffold and two locking mechanisms;

FIG. 2 is a side view of one of the locking mechanisms of FIG. 1 showing the locking mechanism in a locked position wherein the locking mechanism is engaged with the floor;

FIG. 3 is a front view of the locking mechanism of FIG. 2;

FIG. 4 is a side view of the a floor-engaging member of the locking mechanism of FIG. 2 showing the floor-engaging member in a locked position;

FIG. 5 is a front view of the floor-engaging member of FIG. 4;

FIG. 6 is front view of one of the locking mechanism of FIG. 1 with portion cut away and showing a guide portion, extension spring, and a second plunger of the locking mechanism; and

FIG. 7 is a side view of another embodiment of a locking mechanisms of the present disclosure, the locking mechanism including an indicator coupled to a first portion and indicator on a second plunger, the view showing the locking mechanism in a locked position wherein the locking mechanism is engaged with the floor.

DETAILED DESCRIPTION OF THE DRAWINGS

A scaffold assembly 10, shown in FIG. 1, comprises a scaffold 12 with casters 14 coupled to the legs 18 of the frame 12. A support frame 22 is also coupled to the scaffold 12, the support frame 22 supporting a support deck 24. The scaffold assembly 10 further comprises two locking mechanisms 28 coupled to the scaffold 12. Each locking mechanisms 28 is accessible by a worker on the support deck 24 of scaffold assembly 10. The worker engages and disengages the locking mechanisms 28 from the support deck 24. Illustratively, while two locking mechanisms 28 are provided, it is within the scope of this disclosure to provide any number of locking mechanisms 28 as well as a single locking mechanism 28 on scaffold 12.

Henceforth, reference is made to only one locking mechanism; however, the structure of the other locking mechanisms 28 is the same. The locking mechanism 28 is actuable between an unlocked position (not shown) wherein a runner 52 of a floor-engaging portion 56 is spaced-apart from a floor 58 supporting the scaffold assembly 10 and a locked position (shown in FIG. 1) wherein the runner 52 is engaged with the floor 58. In the locked position, locking mechanism 28 impedes movement of scaffold assembly 10 relative to the floor. The runner 52 of floor-engaging portion 56 illustratively comprises rubber which deforms as the runner 52 engages the floor 58. In other embodiments, the runner 52 may comprise any of a number of materials which have viscoelastic properties such that the runner 52 deforms under load. Deformation of runner 52 increases the surface area of contact between runner 52 and floor 58 and tends to create a spring-action effect maintaining the runner 52 in contact with floor 58. The runner 52 may take any shape or size sufficient to engage floor 58. The runner 52 may be round, as illustrated, or elongated. Also, runner 52 may have a variety of types of surfaces for engaging floor 58.

Locking mechanism 28 further comprises an bias member 46 (shown in FIGS. 2, 3 and 6) which is compressed when locking mechanism 28 is engaged with floor 58 such that bias member 46 exerts a substantially constant and known force on floor 58. In the illustrative embodiments, bias member 46 is an extension spring; however, it is within the scope of this disclosure to use any of a number of devices to provide bias and disclosure of an extension spring should not be considered limiting. Bias member 46 engages a first plunger 40 and a second plunger 48, with the bias member 46 urging first plunger 40 and second plunger 48 apart. First plunger 40 is coupled to an actuator 38 which is utilized by a worker to engage and disengage locking mechanism 28 between locked and unlocked positions. In the illustrative embodiment, actuator 38 is a locking clamp such a Model 624 Straight Line Action Clamp from DE-STA-CO Industries of Madison Heights, Mich.

Referring now to FIGS. 2 and 3, first plunger 40 is moved by actuator 38 in two directions as depicted by an arrow 60. Movement of the first plunger 40 is generally perpendicular to floor 58 and first plunger 40 articulates between a locked position (as shown in FIGS. 2 and 3) and an unlocked position (not shown). In the unlocked position, the first plunger 40 retracts generally upwardly and away from the floor 58 such that runner 52 is disengaged from floor 58. When actuator 38 is in the locked position shown in FIG. 2, a handle 62 of actuator 38 is in a position which maintains engagement of runner 52 with floor 58 (i.e. the locked position). To disengage locking mechanism 28, a worker must actuate the handle 62 of actuator 38 upwardly in the direction of an arrow 64 (shown in FIG. 2) which then retracts first plunger 40 and thereby disengages runner 52 from floor 58. While the illustrative embodiment is configured such that actuation of handle 62 of actuator 38 upwardly retracts plunger 40, it should be understood that in some embodiments, actuator 38 may be configured such that the operation of actuator 38 may be reversed and movement of handle 62 upwardly may extend plunger 40.

First plunger 40 includes a main portion 43 and a guide portion 44 which passes through the center of bias member 46 and is received in second plunger 48. Second plunger 48 includes an aperture 74 (shown in FIG. 6) through a first end 50 of second plunger 48, aperture 74 is sized to allow guide portion 44 to pass through aperture 74. A retainer 72 is coupled to guide portion 44 and is located within second plunger 48 vertically below first end 50 of second plunger 48. Retainer 72 is larger in diameter than aperture 74 in second plunger 48 and thereby retains second plunger 48 on guide portion 44 when locking mechanism 28 is disengaged from floor 58, lifting second plunger 48 and floor-engaging portion 56 upwardly. First plunger 40 also includes a flange portion 42 is coupled to guide portion 44. Flange portion 42 defines a drive end 49 of first plunger 40. Bias member 46 engages drive end 49 of flange portion 42 and a top surface 50 of second plunger 48 such that the force of bias member 46 urges second plunger 48 away from first plunger 40.

Guide portion 44 includes a threaded portion 45 which is threaded into female threads (not shown) in a lower end 47 of main portion 43 of first plunger 40. Flange portion 42 also includes female threads (not shown) and is adjustable along the length of guide portion 44 to change the relative spacing between drive end 49 of flange portion 42 and first end 50 of second plunger 48. This facilitates adjustment of the operating length of locking mechanism 28 as well adjustment of the pre-load of spring 46 and thereby allow user to adjust locking mechanism 28 to develop sufficient force of engagement with floor 58 to immobilize scaffold assembly 10 from rolling relative to floor 58.

When locking mechanism 28 is actuated to engage floor 58, runner 52 engages floor 58 before actuator 38 reaches the second, locked position. During a portion of the actuation, first plunger 40 continues to actuate while runner 52 and second plunger 48 are engaged with the floor 58. Guide portion 44 extends into second plunger 48 and bias member 46 is compressed. When the locking mechanism 28 is disengaged from the floor 58, guide portion 44 engages second plunger 48 as shown in solid in FIG. 6. During movement of actuator 38 to the locked position, retainer 72 of guide portion 44 of plunger 40 spaces apart from end 50 of second plunger 48 as shown in phantom in FIG. 6. The force of engagement of locking mechanism 28 to floor 58 is determined by the amount of the compression of runner 52 and bias member 46. This effects a spring-loading which helps to maintain runner 52 in contact with floor 58 with a generally constant force. In some embodiments, floor-engaging portion 56 may be omitted and second plunger 48 may engage floor 58 directly.

Referring now to FIGS. 4 and 5, floor-engaging portion 56 further includes a threaded portion 54 which is a male thread received into a female thread (not shown) in second plunger 48. Threaded portion 54 allows adjustment of the working length of locking mechanism 28 which defines the amount of loading of locking mechanism 28 to floor 58. In some embodiments, flange portion 42 may include female threads and guide portion 44 may include male threads to permit additional adjustment of the relationship of second plunger 48 to first plunger 40 and thereby additionally control the loading of locking mechanism 28 to floor 58.

Referring again to FIG. 1, locking mechanism 28 is coupled to scaffold 12 through an upper mounting bracket 30 and a lower mounting bracket 32. Upper mounting bracket 30 comprises a frame engaging member 66 and a guide support 34. Actuator 38 is coupled to guide support 34. Guide support 34 has an aperture through which first plunger 40 passes when actuated by actuator 38. Actuator 38 is retained on guide support 34 by a jam nut 68 which engages a threaded portion 70 of actuator 38. Jam nut 68 engages guide support 34 when tightened to secure actuator 38 to guide support 34 through frictional interference between jam nut 68, threaded portion 70, and guide support 34. Frame engaging member 66 is retained on frame leg 18 of scaffold 12 by bolts 26 and nuts 27.

Second plunger 48 is retained by a guide tube 36 which is coupled to two guide supports 34 on the lower mounting bracket 32. Lower mounting bracket 32 also includes a frame engaging member 66 which is coupled to frame leg 18 by bolts 26 and nuts 27. Guide tube 36 has an inner diameter which is slightly larger than the outer diameter of second plunger 48 and is sized such that second plunger 48 moves within guide tube 36 freely. Lower mounting bracket 32 positions guide tube 36 in an orientation that is aligned with the aperture in the guide support 34 of the upper mounting bracket 30 so that the first plunger 40 and second plunger 48 are maintained in an orientation which is generally perpendicular to floor 58. In the illustrative embodiment, guide supports 34 are welded to frame engaging member 66. However, it is contemplated that guide support 34 may be coupled to frame engaging member 66 through any of a number of fastening methods including screws, bolted joints, adhesives, or hook and loop fastening systems. Guide tube 36 is coupled to guide supports 34 through welded joints.

In the illustrative embodiment of FIG. 1, locking mechanism 28 has a fixed length second plunger 48. It is contemplated that second plunger 48 may be a variable length plunger which can be adjusted for different heights of scaffold assembly 10. For example, second plunger 48 may be a two-piece construction with a first portion having a smaller outer diameter than an inner diameter of a second portion so that the first portion may telescopically extend and retract relative to the second portion to adjust the length of second plunger 48. In such a case, the first portion may be lockable relative to the second portion once an appropriate length is selected so that the second plunger 48 has a fixed working length for a particular scaffold height.

In another embodiment of a locking mechanism 128, shown in FIG. 7, a first plunger 140 is similar to first plunger 40 and further includes a first indicator 130 coupled to a main portion 43 and positioned to extend vertically downwardly to cover bias member 46 and a portion of a second plunger 148. Second plunger 148 includes a second indicator 132 which comprises a line which provides an indication that bias member 46 has been compressed sufficiently to provide the necessary force to engage runner 52 with floor 58. Second indicator 132 is positioned such that the covering of second indicator 132 by first indicator 130 indicates that the distance between first plunger 140 and second plunger 148 is reduced to sufficient compress bias member 46. This provides a reference for the adjustment of second plunger 148 and floor-engaging portion 56 so that a user is apprised of the correct adjustment. Bias member 46 has a predetermined length and predetermined spring constant. The force exerted by bias member 46 is determined from the spring constant and the amount of compression of the spring. The position of the first indicator 130 and second indicator 132 are predetermined so as to provide the appropriate compression of bias member 46 to develop sufficient force to lock the scaffold assembly 10 in place. As such, the position of line or second indicator 132 may be changed depending upon the spring constant of the particular extension spring being used. It should be understood that while a tube and line are used in the illustrative embodiment, any of a number of indicators may be used to provide an indication that bias member 46 is sufficiently compressed to develop sufficient force in locking mechanism 28.

As shown in FIG. 1, scaffold assembly 10 includes two locking mechanisms 28 coupled to frame legs 18 at opposite corners of scaffold assembly 10. Multiple locking mechanisms 28 may be utilized about scaffold assembly 10 to improve the stability of scaffold assembly 10 when locking mechanisms 28 are each engaged with floor 58. Additionally, the length of guide supports 34 may be varied in certain applications to control the engagement point of runner 52 to floor 58 relative to frame leg 18 and thereby casters 14. In some embodiments, a plurality of locking mechanisms 28 may be utilized with each of the plurality of locking mechanisms 28 coupled together such that a single actuator 38 may actuate the plurality of locking mechanisms 28.

Although certain illustrative embodiments have been described in detail above, variations and modifications exist within the scope and spirit of this disclosure as described and as defined in the following claims. 

1. A locking mechanism for a scaffold comprising: a mounting bracket configured to be mounted to a scaffold, a first plunger coupled to the mounting bracket, and a second plunger coupled to the first plunger; wherein the first plunger is moveable relative to the second plunger between an unlocked position wherein a first end of the second plunger is engaged with a second end of the first plunger and a locked position wherein the first end of the second plunger is spaced-apart from the second end of the first plunger.
 2. The locking mechanism of claim 1, wherein the locking mechanism further comprises a bias member interposed between a portion of the first plunger and a portion of the second plunger to urge the first and second plungers apart.
 3. The locking mechanism of claim 1, further comprising a floor-engaging member configured to engage with a floor supporting the scaffold.
 4. The locking mechanism of claim 3, wherein the floor-engaging member is spaced-apart from the floor in the unlocked position and is engaged with the floor in the locked position.
 5. The locking mechanism of claim 1, further comprising an actuator coupled to the first plunger, the actuator configured to move the first plunger between the locked and unlocked positions.
 6. The locking mechanism of claim 5, wherein the actuator comprises a toggle lock handle.
 7. The locking mechanism of claim 1, wherein the first plunger further comprises a first indicator and the second plunger further comprises a second indicator, the spacing between the first indicator and second indicator indicative of the relative position of the first plunger to the second plunger.
 8. The locking mechanism of claim 7, wherein the first indicator comprises a tube and the second indicator comprises a line.
 9. The locking mechanism of claim 8, wherein the first indicator is spaced-apart from the second indicator when the second plunger is in the unlocked position and the first indicator is aligned with the second indicator when the second plunger is in the locked position.
 10. A locking mechanism for a scaffold comprising: a mounting bracket configured to be mounted to a scaffold, a first plunger coupled to the mounting bracket, a second plunger coupled to the first plunger and moveable relative to the plunger, a spring coupled to and positioned between a drive end of the first plunger and a first end of the second plunger, and wherein the locking mechanism is moveable between an unlocked position where the first end of the second plunger is spaced-apart a first distance from the drive end of the first plunger and a locked position where the first end of the second plunger is spaced-apart a second distance less than the first distance from the drive end of the second plunger.
 11. The locking mechanism of claim 10, wherein the first plunger further comprises a first indicator and the second plunger further comprises a second indicator, the spacing between the first indicator and second indicator indicative of the relative position of the first plunger to the second plunger.
 12. The locking mechanism of claim 11, wherein the first indicator is spaced-apart from the second indicator when the second plunger is in the unlocked position and the first indicator is aligned with the second indicator when the second plunger is in the locked position.
 13. The locking mechanism of claim 12, wherein the distance between the first plunger and second plunger when the locking mechanism is in the unlocked position is adjustable.
 14. A scaffold comprising: a frame, a platform supported by the frame, a plurality of wheels coupled to the frame, and a locking mechanism coupled to the frame, the locking mechanism moveable between a first position wherein the locking mechanism is configured to engage with a floor supporting the scaffold and a second position wherein the locking mechanism is configured to be spaced-apart from the floor.
 15. The scaffold of claim 14, wherein the locking mechanism is spring-loaded.
 16. The scaffold of claim 14, wherein the locking mechanism further comprises an actuator moveable between a locked position and an unlocked position, a first plunger coupled to the locking handle, the first plunger including a guide portion engaging a second plunger, an extension spring engaging a portion of the first plunger and a portion of the second plunger, the extension spring urging the first plunger and second plunger apart, wherein the second plunger is configured to engage the floor in the locked position and be spaced-apart from the floor in the unlocked position.
 17. The scaffold of claim 16, wherein the first plunger further comprises a first indicator and the second plunger further comprises a second indicator, the spacing between the first indicator and second indicator indicative of the relative position of the first plunger to the second plunger.
 18. The scaffold of claim 17, wherein the first indicator is spaced-apart from the second indicator when the second plunger is in the unlocked position and the first indicator is aligned with the second indicator when the second plunger is in the locked position.
 19. The scaffold of claim 18, wherein the distance between the first plunger and second plunger when the locking mechanism is in the unlocked position is adjustable.
 20. A method of operating a locking mechanism coupled to a scaffold having a plurality of wheels and moveable relative to a floor supporting the scaffold, the method comprising the steps of: positioning the scaffold in a work position, adjusting the locking mechanism so that an first indicator on a first portion of the locking mechanism is aligned with an second indicator on a second portion of the locking mechanism when the locking mechanism is in a locked position, and actuating the locking mechanism such that the floor-engaging member engages the floor to immobilize the scaffold from rolling with respect to a floor supporting the scaffold. 